<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!--请将h1下面的所有em元素改成红色 中间一定要有空隔 如果大于就是-->
    <style>
        h  em{
            color: red;
        }
    </style>
</head>
<body>
    <h>
        this is a
        <em>儿子</em>
        <strong>
            <em>孙子</em>
        </strong>
        heading
    </h>
</body>
</html>